The present invention relates to a method of producing high-quality polyethylenepolyamines, in particular, decolorized high-quality polyethylenepolyamines.
Polyethylenepolyamine is a useful amine compound to be used for paper strength resin, epoxy-curing agent, lubricating oil additive, surfactant, etc. in large quantities.
Polyethylenepolyamines (hereinafter abbreviated as polyamines) are produced through a reaction between ethylene dichloride (hereinafter abbreviated as EDC) and ammonia and/or relatively lower ethyleneamines such as ethylenediamine (hereinafter abbreviated as EDA) or a reaction between ethanolamines and ammonia and/or relatively lower ethyleneamines such as EDA.
The polyamines obtained through these producing processes are usually mixtures and fractionated by distillation, but their distilled fractions have yellowish brown to dark brown color. This is considered to be due to the impurities, leading to decreased commercial value, if left as they are.
As the measures for solving this coloring problem, a lot of decolorizing methods of polyamines have been proposed.
For example, methods of using metal or its salt such as a method of treating polyamines with potassium hydroxide (specification of U.S. Pat. No. 3,595,921), a method of adding reducible metal like zinc, tin or aluminum and sodium hydroxide or potassium hydroxide to polyamines to treat under heat (Japanese Patent Publication No. Sho 44-2209), a method of adding Zinc and water to polyamine at room temperature to 150.degree. C. to treat (Japanese Patent Publication No. Sho 44-4768) and a method of simply adding zinc alone to treat under heat (Japanese Patent Publication No. Sho 45-33163) are disclosed, moreover methods of using activated carbon or ion exchange resin such as a method of treating polyamine with activated carbon at high temperature (specification of U.S. Pat. No. 3,723,529) and a method of treating with-sulfonic acid type cation exchange resin (specification of U.S. Pat. No. 4,731,165) are disclosed, and further methods of hydrogenating with catalyst such as a method of treating with acidic zeolite (specification of U.S. Pat. No. 4,737,243) and a method of hydrogenating using nickel, cobalt, palladium or ruthenium as a catalyst (Japanese Unexamined Patent Publication No. Sho 63-101421), and the like are disclosed.
However, all of these methods exert no sufficient decolorizing effect and are not satisfied industrially.
Namely, in the methods of using metal or its salt, expenses for metal run up, leading to disadvantage economically, metal or its salt accompanies with polyamines, thus requiring removal thereof , polyamines are contaminated reversely with metal dissolved out, and the like, hence they cannot be said to be industrial methods. In the methods of using activated carbon or ion exchange resin, deactivation thereof is significant and it is needed in large quantities, which are uneconomical. Also, in the methods of hydrogenating with catalyst, deactivation of catalyst is significant and it is needed in large quantities, which are uneconomical, and there is a danger of lowering the quality of polyamines by decomposed products, hence these also cannot become industrial methods.
For this reason, decolorizing methods of adding hydrochloric acid are proposed. For example, in Japanese Patent Publication No. Sho 50-20047, a method of distilling polyamines in the presence of their hydrochloride is disclosed, and, in Japanese Unexamined Patent Publication No. Sho 57-171939, a method of treating polyamines with their hydrochloride under heat in the presence of water followed by flush evaporation is disclosed.
However, despite that the method described in Japanese Patent Publication No. Sho 50-20047 is relatively economical and decolorizing effect is also not insignificant, large quantities of hydrochloric acid are needed and salt is produced in large quantities as well by neutralization, hence it is not a satisfiable method industrially. Also, the method described in Japanese Unexamined Patent Publication No. Sho 57-171939 exerts relatively high decolorizing effect, but coexistence of low-boiling point water at high temperature brings about high pressure, thus requiring a device endurable pressure. In addition, polyamines obtained by flush evaporation are not of single component and much of low-boiling point components and high-boiling point-components are accompanied, hence they cannot become merchandise if left as they are, requiring to distill again for separation, which cannot be said to be economical method.
As descried above, all of the conventional methods are not ones that effectively and efficiently decolorize polyamine and produce high-quality polyamine, hence they were not satisfiable.
The invention was made in view of the subjects aforementioned, and the purpose is to provide an industrial producing method that exerts high decolorizing effect and affords high-quality polyamines economically.
The inventors investigated diligently on a method of producing high-quality polyamines, concretely on an economical and industrial decolorizing method.
As a result, it was seen that, for economically obtaining high-quality polyamine, concretely, sufficiently decolorized polyamine, a decolorizing method adding-hydrochloric acid was effective. When obtaining polyamines by distillation, however, high-boiling point polyamines could not be decolorized sufficiently, though low-boiling point polyamines were decolorized sufficiently.
There, as a result of further investigations, it was seen that, at the point of time when low-boiling point polyamines had been separated by distillation, alkali metal hydroxide was added to residual liquor after distillation to once neutralize hydrochloric acid existing in the residual liquor after distillation and then distillation was performed again to separate high-boiling point polyamines, thereby all polyamines from low-boiling point polyamines to high-boiling point polyamines could be obtained in the state of being sufficiently decolorized.
Moreover, it was seen that, when using halogen acids such as hydrobromic acid and hydroiodic acid in place of hydrochloric acid to be added, same or higher decolorizing effect than that with hydrochloric acid could be obtained.
From the investigation results as above, it has been found that the subjects aforementioned can be solved and the goal can be accomplished by treating polyamine under heat in the presence of halogen acid, then performing distillation to separate low-boiling point polyamines, next, adding alkali to the residual liquor after distillation to neutralize and performing distillation again to separate high-boiling point polyamines, leading to the completion of the invention at last.